Neutronic reactor operational method and core system



July 19, 1960' c. awiNTERs ETAL 2,945,794

NEUTRONIC REACTOR OPERATIONAL METHOD AND CORE SYSTEM Filed Nov. is, 1952 4 Sheets-Sheet 1 BY Josep/7 6'. Culver l Robe/' H W//son July 19,Y 1960 c. E. WINTERs ET AL NEUTRONIC REACTOR OPERATIONAL METHOD AND CORE SYSTEM 4 Sheets-Sheet 2 Filed Nov. 18, 1952 Clifton B. Graham Jaseph 6. Cu/ver d @ober- H. Wi/.son

ATTORNEY 7' tien effe neutm n t greater massithanan alphaparticle, which splitting is ac y gatesystemfcapable of gen n .52,945,794 NEUi-*Rom REAcToR'orERATIoNAL u -ANncoREsYs'rm/r s Pateptelsuiy is, teso Through; serving to decelerate theneutron's to `much more eiiectivezenergylevels, Ysuch Vincorporated neutron-l charles nwinfers, `Clifton. B. Graham, Joseph s.'cu1ver,

and Robert HfWilson, Oak Ridge, Tenn., assignors Vto l. theV United States` of America as'represented 4bythe United States Aternic Energy Commission As sknoWn, certainpalticular isotopes, termed'iissionfv able materials-prominent'among -which are uranium 235, plutonium 2x39, uranium 233, and othersand all of which, Vby ,definitic`m, are capable of undergoing fission upon captureofgafslow neutron-,upon being subjected to f neutron bombardment, absorb neutrons of indiscriminate e energiesuand thereupon undergo 'ssion. In fission,l the j atonific `nucleus "of the iissionable isotqpe,rupon thea'bsorp-` splits Ainjto a plurality of fragments of companied by the` releasenoffa relatively enormousamount of energy a ,pl uralitylofsneutrons. By'fvirtue of the iis'sionreactionjsl generatingfmorejnew neutrons than it`v i consumes, it is possible, Lbyjamsassing sutiicient `iissionavble material under appropriate,conditions` to form an {aggrei ng neutrons at a rate equalf 2` "5 to lor greater than thatlat which they arerbeing lostto the l I v Systemes kthe` re'vltfef .abSmtiOil ilflelsysternfcr. leak the system, and4i`consequently, capable oftna'intaininga selsif#sustaining Yneutron-induced chain fission e 're-v v' action.A Such an iam'assment constitutes theY essence of a'gneutronic reactoruand may be `termed theLYcore of a i i e neutronicreaetor; ,tli'emass of ii'ssionablematferialsuicient-to generateeneutrons at a frate Yequal to; or greaterA than, loss-.is referred toas afe'ritical mass, ora super-V critical mass;7 respeetively. Y

While the neutrons generated in the ssio n reaction are generally of Vquiteflngh kinetic energy, it happens that the propensity of issionable isotopes for absorption of neutrons leading to fission prominently increasesv with decrease in the kinetic energyof the neutrons, with generally the greatest susceptibility" to such absorption obtaining in the instance of neutrons which are so slow as to be in substantial thermal equilibrium with the system (e.g., neutron kinetic energy of ca.`0.025 electron volt at 15 C.). Accordingly, it has: become customary practice in most circumstances to incorporate Vin the yama'ssment a substantial proportion of a material effective in markedly reducing the'kinetic Venergy-of neutrons upon their encountering Athe same, without contemporaneously absorbing neutronsto any excessiye degree.e` Such 'ai material is termed aneutron-moderantfand may be moreprecisely deiinedlas anon-gaseous" material for which the, ratio is greater than l0,wherein` rithm o'f'pthe'ener'gy of la, fastneutronper el-astic"`coll1sion with' the materilgdglis the slow neutron elastici scattering f cross-section per 'atoniof the material, and aa is the slow Aneutron'.capture cross-section per atomof the material.

.Eisthe average loss in loga-` Y Y v `moderant"willbeneficially afford sizeable-reductionin the METHOD 5 'material necessary to constitute a ing thermal vequilibrium preponderate, neutron-moderant materials are usually satisfactory for constituting such a neutron'reector. t. i

Among the various practical uses of the neutronic reactonparticularly prominent is its application as `a radically-advanced-v source of thermal power... Significantly, in fission, theispecific energy content liberatable by nuclear reaction is enormous; thequantity -andrate of thermal energy producible., per unit amount of ssionable material consumed, vastlysurpass those produciblebyconventional chemical combustion: For example, in neutron-induced fission of the 23,5 isotope of uraniurmthe amount of thermal energy produced per pound of Afuel consumed is of the Aorder of 2,000,000 times thatproduced by aviation gasoline. Consequently, even in brisk `operation as a heat sourceareactors fuel depletionis comparatively*insignifi- VVcant, such that the initial charge of fuel/is ordinarily sufiicient vto sustain the reaction indefinitely; with such'ja "furna ce, the need for constantly replenishing thefuel is virtually eliminated. Similarly, `since the chain fission reaction `inherently capable of operation at `intensities i :to Ithose orders manifested bythe stellartempera#V `tures attained in 'atomic "bombs,- the reactor as a heat s ncmn-ally adptedto operation at` virtually any de ,red -ra-t of energy release andtemperaturelevel ."lfhl' .if'trudvreafid materials cf Censtruefienan withstand.:

:Further-more, Pa chain fission reacting system@ faclljnitsfof` iunusllal compactness; especiallywhengross amounts orf' eirtraneous-materials are ex'clud,i `from the amassment,

Operating featorae maygwell bia-Smaller 111211 a few Y 'cubic'feet infvolume;` By virtue of `these attributes, theY nuclearreactorWhas 4proven exceptionally promising for u seasfthe ultimate heat source for power plants, particularly for stationary electric generating plants, and for mobile, propulsive power plants forV ships andaircraft; of especial significance in4 mobile applications, Where the afforded elimination of the yneed for `any ysubstantial amount of replacement fuel renders insignificant the vformerly-limiting fuel capacity consideration, practically lintitiess'range of such craft may be realized.

'In the development and design'of reactors for such purpose, interest and etort has been directed largely -alongrthe lines of an -am-assment of both issonable materialv iand neutron moderant in solid form, through which a fluidheat-transfer medium would be passed to extract theheat generated. Typical of this mode of construction,

the 'reactor core would comprise a matrix of clustered` blocks of -alneutron moderant in ceramic or metal form; having disposed in"ho1lovv s therein -a multiplicity of masses of iisfsionable' fuel also in ceramicorjmetal `forni,",through Y Yquantity of heatftra-nsfer medium, extraneous to theneu` tronic reaction, Within the core; ordinarily, the. medium i Vnot onlyy occupies considerable space,Y thusadding to` the f sont reducing the ssionable n b necessary volume of the core, but also fruitlessly absorbs sizeable proportions of the neutrons generated-on both counts, disadvantageously necessitating considerable increase in the `amount of fissionable material required to constitute a critical mass in such core. Too, being 'constituted Yof an agregation of solid elements, such core, espe-` cially in mobile applications subject to tilting and jarring, needs considerable internal support structure-againof extraneous materials, similarly occupying valuable space and fruitlessly absorbing neutrons..` Furthermore, to provide suficient thermal force to drive-the great amounts of heat generated per unit volume of core into the heattransfer medium, Yit would be necessary'to maintain the solid portions of the core at temperatures as much as several hundred degrees above the maximum attained in the heat-transfer stream; as a resultat such higher temperat-ures, series taxing of -the thermal stability of the solid core elements would result, attendedby Warpage, breakage, and other mechanical failures, although all the while the heat was being delivered outside the core by the heatV` transfer medium Vat a temperature unproiitably several hundred degrees lower than that at which the core operates. Another prominent difficulty regularly encountered with'solid-cored reactors arises in Vconnection with a customary periodic decontamination of the fissionable fuel. Since a number of the fission products-ie., theV fragments formed upon fission-and their radioactive decay products, comprising isotopes Within the range of atomic numbers of'30' to 63--are voracious absorbers of neutrons, continued self-sustenance of the neutronic reaction requires that fission product accumulation be kept at a very low level; in practice, each unit of fssionable material upon becoming sufficiently contaminated is re'- xnoved, to be processed for elimination of the fission productv contamination and isolation ofthe purified bulk ofssionable material for reuse in the reactor. Disadvantageously, a solid-cored reactor, this normallyV invlves either aperiodic, complete shut down `and major f dismantlingV of the, reactor, or an undesirably ponderous and complex ymechanism,associated with the core for ref placement and withdrawal of individual fssionable `fuel elements jasfibecomes'necessary *while maintaining con-YV tinued'operation ofthe reactor.

frtlierfinformationpand details as to the theory,`v

construction, fand operation of neutronic reactors generally, and solid-core reactors in particular, reference may be made tothe following sources: A

"The Science and lngineering of Nuclear Power, edited by'Clark Goodman, vol 1 (1947), and Yvol. 2 (1949)Addison-Wesley; .Y

p First Detailed Description of the AEC Research Reactors, Ain Atomics, vol. 6, November-December 1950; and co-pending applications of the common assignee:

S.N. 578,278, filed February 16, 1945, in the names of Enrico Fermi and Miles C. Leverett, for A Chain Reacting System, now Patent No. 2,837,477, issued June 3, 1958; Y

p' S.N. 596,465, filed May 29, 1945, in the names of Enrico Fermi and Leo Szilard for Air-Cooled Neutronic Reactor, now Patent No. 2,836,554, issued May 27, V1958; A S.N. 194,331, filed November-6, 1950, in the name of George A. Anderson, for Neutronic Reactor, now Patent No., 2,780,596, `issued February 5, 1957; y p e ,.'S.N.` 206,592, filed January y18, 1951, in the name of George A. Anderson, for -Fuel Element Loading Apparatus for Neutronic Reactors, now Patent No. 2,794,562.

ToWa'd circumventing some or all ofthese shortcomings of the solid-core system, resortto liquid form for both the fissionable fuel and moderant has long been partic'ularly appealing. Since both normal water and deuterium'oxide (heavywater) are recognizedV tofbe superior moderants, aqueous solutions of uranium or plutonium, particularly uranium or plutonium highly enriched in one of its fissionable isotopes, have attracted special interest. Beneficially, with both ssionable-fuel and moderant in a single liquid solution: there need no longer be any solid in the core to warp or crack; in place of complex internal support structure, a simple tank to contain the liquids is all that is necessary; and removal and replacement of portions of the fuel for decontamination, when necessary, is simply eected by draining and pumping of liquids. 'Further benefits derive upon circulating the 1 liquid fuel-moderant, in substantially subcritical distribution, through an external circuit for recovering its generated heatgthen, the need for an extraneous coolant within the core is -advantageouslyeliminated, and the produced heat may be recovered vat almost the same high tempera-ture at which it was generated within the core.

y543, issued July 15, 1958;

Moreover, by continuously or periodically routing a portion of the liquid fuel stream, in its passage external the core, through decontamination processing, even greater simplicity and convenience is achieved.

I PriorV to the present invention, a number of small-scale experimental reactors, employing an aqueous solution of -arsulfate or nitrate of uranium or plutonium highly enriched in one of its ssionable isotopes as their fuelmoderant, and adapted-to operation at merely quite low powerdensities, were successfully built and operated. In these reactors, the aqueous solution was either disposed in, or circulated through, a tank encased in a neutron refiector constituted of berylliumfoxide and/or graphite; further details are available in co-pending applications of the common assignee: y

lS.N. 623,363, filed October 19, 1945, in the name of RobertF. Christy, for Reactor, now Patent No. 2,843,-

K SN. 75l/1,734, filed June 2, 1947, inthe names of H. C. Urey, K.v Cohen, and' F. T. Barr, for Improved Method and `Apparatus for'Produ'cing Energy by Nuclear Fission; andin the following publication First Detailed Descripton of, 'AEC Research Reactors (supra). .Y However; although operation at verylow power levels was 'found satisfactory, nevertheless at higher operational powerv levels ,the aqueous solution-form of reactor -core proved to be seriously plagued by an inherentcharacter! power production. That is, as van adjunct to the fission reactionpthe water of the aqueous solution in the. core is progressively decomposed into principally hydrogen andoxygen gases-as well as a small amount of hydrogen peroxide-as a result of the intense ionization produced by the radioactive emanations and fission fragments emitted upon each ssicnj The magnitude o f the resultant gas evolution is by'no means insignificant; in operation at a power generation rate of 1000 kilowatts and at atmospheric pressure so much as'fseveral liters per second of gas would be evolved. Gas formation and bubbling of such magnitude directly within the critical amassment lgreatly detracts from general-controllability ofthe reaction; the gas bubbles would tend to displace much of the fuel solution from the core tank toward rendering the amassment subcritical and inoperative, and ifea core tank sufficiently larger to accommodate a critical amassment of fuel solution despite the bubbling were sub stituted, lthe resulting system would be susceptible, upon any momentary subsidence in the bubbling, to exceeding the bounds of all reasonable control means so as to run away in a perhaps catastrophic, uncontrolled neutronic fission ,reaction-uncondonabl a violent and j,erratic careening4 of .the reaction between inoperative subcriticality and calamitous excessive supercriticality. As yan added hazard, the evolved gas is, in itself, explosible, and thus mote `amodest extent of recombination of the gases bach into water. Likewise, various catalytic and combustion techniques for effecting controlled recombination or the gases, toward reducing the explosion hazard, have been devised and developed. Nevertheless, although theseverity of the action can thereby be subdued, substantial bubbling has still persisted, in =a nature still fundamentally unsatisfactory to effective control of ythe iission reaction at high power densities and consequently still repugnant `to the desired application to power production. Particularly objectionable, the generated gasbubbles take random and erratic paths in their gradual rise to the surface of the liquid, which results -in local non-,uniformity and non-symmetry in distribution ot rissionable material, with concomitant like local unbalance in the distribution of A the rate of ssion reaction; This effect becomes especially serious in view of the lingering rate of ascentof the lbubbles, which represents a" protracted residence time for each bubble in the solution. The aggregate elect is deleterious `oscillation in the rate of reaction throughout the core, and, as la result, large and rapid fliuctuations` in the overall rate of iissioning. Furthermore, in rising, the

liquid-displacing Ibubbles progressively gainthe'company of other bubblesat each higher level, and -tlius increase in number toward V'the top; this resultsin a Vnon-'symmetrical overall distribution of ssionable ueLwith the degree of non-symmetry varying with the overall rate of reaction;a condition which further contributes to oscillation and uctuations in reactivity. YConsequently, there has been an increasing desire that new, effective reactor means be round for finally overcoming the4 frustration `of this gas-evolution difficulty, and aiording practical and elective application of reactors employing fuel in aqueous liquid form, :at appropriately high specic heat generation rates, to practical power production.V

Accordingly, one object of the present inventionfis to `provide' a new and improvedV method for'voperating a neutronic reactor employing issionable fuel and moderant `in `liquid formi, which vlargely avoids and overcomes serious di'iculties whichfwould otherwiseiattendradiation-'induced gas evolution ordinarily 'occurring f Within the core of'such reactors.V i

Another object is to provide a new and improved core system for sucht` a reactor particularly adaptedtoimpleinent such method.A l l Afurther object isf'to provide such a method and core system especially suited to afford such 'improvement where the iissionable fuel and moderantare in aqueous solul' of such type, of lappropriate fitness and suitability for practical-scale power production. Y

Yet a further Vobject is to provide such a reactor suitable for economic and convenient fabrication, in a large measure, from conventional steam-plant, and chemicalprocessingvessels, apparatus, ,andl plumbing, available in Y standardstock on the market. l

` Additional objects will become apparent hereinafter. In accordance with the present invention, for improved operation of a neutronic reactor comprising a liquid containing'rs'si'onable material adapted "to bernaintained in an arnassmentand While so amassed, toengage in self-sustaining chain iission reaction withc'oncoinitant substantial" gas evolution, a fundamentally-advanced method comprises maintaining said liquid -in said amassment in ,rotational flow about a principal axis of thefarnassment at ya sui'licient velocity Vto provide a vortex, and discharging-evolved gas as it concentrates within the cavity of the vortex. In establishing such a vortex, the issionablefuel-containing liquid in the amassment, upon being maintained in rapid axial rotation, is thrust outward toward the periphery of rotation by the resulting centrifugal force, and accordingly tends lto vacate and form a cavity along the axis of rotation; thereupon, evolved gases, by virtue of their low density,` are centripetally displaced toward the axis and into such cavity, from where the gases may be discharged as they concentrate. Importantly, upon such vigorous rotation, supergravitational fields manyY times that of normal gravity are centrifugally established. Under the correspondingly intensified inuence toward centripetal bubble displacement concomitant to such fields of force, the bubbles of evolved gas, instead of lingeringly and Wanderingly rising through the liquid, arecaused to dart swiftly to the cavity; as a result, the comparable amount of gas dispersed in the liquid at any one time is markedly decreased, and erratic and iluctuating non-uniformity in ssionaible material distribution is enectually minimized. To the same end, for a .given general' amassment, the-distance through the liquid body each bubble must traverse is only a fraction of that in a quiescent tank, thus serv-ing to further reduce the residence time of the bubbles in the liquid. Moreover, since all bubble migration is toward the 'central axis, overall non-symmetry of ssionable material distribution through the amassment is eliminated, thereby doing away with 'the :associated conditions favorable to initiating and sustaining oscillatory fluctuations in ssion rate throughout the amassment. v Despite the' erratic nature ofv vortices, especially/'When viewed in connectionwith` the precise dependence of reactor criticality upon the constancy of volume and spatial `disposition of the solution amassed, applicants have discovered" and` colnprehenimproved reactor core system particularly advantageous thereby entirely eliminated, the volume v`of fuel liquidiin 'the amassment is maintainable constant and steady.

for implementing thisamethod, `for application in a neu'- Vtronic reactor comprising `a liquid containing ssionable material adapted to continuously llow as a stream through-,a container means and to engage in self-sustaining chain fission reaction with concomitant substantial gas evolution While within said container Vmeans,

Van improved container means comprises an internally-V unobstructed closed container having an internal geometry of revolution about-a principal axis; liquid-inlet duct means communicating substantially tangentially with the interior of said container; means deiining a gas outletV substantially axially concentric with, and at an vaxial extremity of, said container; and means defining an annular liquid-outlet port substantially axially concentric with, and at the same axial extremity of, said container as, and surrounding, said means deiining a gas-outlet por-t.- Advantageously, with such a-core system the rotation establishing the vortex is provided without the need for any neutron-absorptive mechanical impeller means within the core; furthermore, from a hydrodynamic standpoint, the actions of both the tangential introduction and the axial discharge of the, liquid each complementarily contribute to maintaining the vortex in motion. Benencially, the axialgas-outlet port will register "naturally with an extremity of the cavity of the vortex, thereby affording discharge of evolved gas as it" concentrates within the cavity;,with all opportunity for progressive accumulation and 'sudden dislodgement ofigasbeing Moreover, the operation'of such container meanspositively counteracts the occurrence of hot spots and local boiling in the solution; any localregion of liquid react;

ing too fast and becoming too hot, becomes less dense than the surrounding liquid and consequently ismore rapidly forced centripetally toward the center of the vortex and out the liquid-outlet port, thus avoiding boiling or other trouble therefrom.

In short, by virtue of forcefully regimenting the encountered gas-evolution into a steady and stable effect, as well as sharply curtailing residence time of bubbles in the amassed solution, the instant technique substantially extends upwardly the specific power generation rates at which liquid reactors may practically be operated; hence, when employed in conjunction with pressurization and similar prior means for counteracting the bubble problem,

liquid reactor operation well into therange of practical,

power production rates is liberally afforded. For example, such a system has proven eminently successful in practice as embodied in a full scale prototype reactor, adapted to serve as the ultimate power source of an electric generating plant, utilizing a circulating aqueous U235-enriched uranyl sulfate solution, adapted to operate at a temperature of ca. 250 C., a pressure of 1000 p.s.i. and a reactor operational rate of 1000 kw. By having achieved successful operability, and by providing its significant advantages, the present means clearly represents 'a bold stride forward in the design of neutronic reactors.

In conducting the present method, the specific procedure employed to impart liquid rotation for establishing and maintaining the vortex, is subject to Wide variation. For instance, driving the liquid with. rotating mechanical impellers, constructed of low neutron-absorptive material such as aluminum, incorporated within the core, would be satisfactory. Particularly preferable, though, is the technique of maintainingV liquid rotation by tangential introduction and axial discharge of a. continuous stream of the fuel liquid through a closed core container. In this way, utter simplicity, avoidance of including neutronabsorptive extraneous materials within the core, and assurance that the essential rotation will necessarily continue throughout all times that any fuel liquid is being delivered in regular flow to the core, are achieved. For

`developing a smooth and steady vortex internal-unobstruction and an internal geometry of revolution are in l order for the core container; in this respect, toward avoiding serious eddies, smoothness, regularity, and general convexity of the generatrix of such geometry is especially desirable. While closed cylinders, and prolate and oblate spheroids well satisfy these requisites, the sphere is particularly preferred, not only in that it provides an ideal geometry for stability of a vortex, ybut also, from the neutronic reaction standpoint, it affords the optimum geometry for minimizing the mass of iissionable material required for criticality. Accordingly, the choice means for conducting the present procedure, is a sphere with liquid inlet tangential, say in the equatorial plane, and with liquid outlets at one or both of the poles Generally speaking, the higher the velocity of liquid rotation in the vortex, the better; higher velocities lend themselves to a firmer and more stable vortex, a sharper and more uniform central cavity, and increased rate of gas separation from the liquid.

' Likewise, the particular constitution of the chain reacting system to which the instant technique is applied is subject to considerable variation. Generally, any reactor system containing or circulating iissionable material in liquid form subjectto gas evolution may be beneted. Such benefit extends to system using liquids, both inorganic -and organic, which for the most part consistently suifer suchy radiation-induced decomposition into gases to undesirable degree; systems applying organic liquids, notably hydrocarbons, both as effective solvents for the ssionable material and as able moderants in view of high hydrogen content, are markedly susceptible to radiation decomposition, and thus are especially enhanced. The technique has proven vparticularly advantageousV in cases where fissionable material contained or circulated is in aqueous solution or deuterium oxide solution form, wherein the water or deuterium oxide content serves as the principal neutron moderant. There, it is usually desired that the solution be constituted of a proportion of Water or deuterium oxide sufficiently great to thoroughly attenuate the kinetic energy of the neutrons generated in the fission reaction such that the average energy level of neutrons in the core closely approximates that of thermal equilibrium at the ambient temperature. For this, molar ratios of Water, or deuterium oxide to fissionable isotope greater than the order of to l are appropriate, with the range of about 250-1000zl being particularly preferred; the latter would amount to solution concentration of ca. 10-50 grams U235 per liter. While these concentrations are of quite low fractional molarity, actual solution concentrations necessary to achieve them will be considerably greater where the iissionable isotope is associated with other non-iissionable isotopes of its polyisotopic element-for example, U235 only partially freed of associated U23. Furthermore, with. manifold isotopic dilutions, solubility considerations unobjectionably often necessitate even greater ratios of Water to tissionable isotopesfor example, with deuterium oxide solutions of natural uranium, comprising only about 0.7% U235, molar ratios of D20 or water:U235 within the higher range of 1,000-10,000:'1 become necessary merely to effect complete dissolution. For constituting the solution, the ssionable material should best be in compound form, more particularly, in the form of a uranium or plutonium compound of high solubility and of staunch resistance to the heat and radiations to be encountered, and one which does not contribute components either excessively absorptive of neutrons or susceptible to intense radioactivation. Satisfactory in these respects are uranyl and plutonyl sulfates and nitrates. The volume of fuel solution necessary to constitute a critical mass varies with the parameters affecting the rates of consumption and loss of neutrons therefrom, e.g. geometry of the core4 container, relative volume of the vortex cavity, specific composition and nuclear properties of the solution, effect of solution impurities, identity of material of core container and other materials proximately surrounding the amassment, and the like. Such volume is quite accurately calculable, though, on the basis of known and accepted nuclear engineering theory; typically, for example, for a spherical core geometry, a slim vortex'cavity,

and a fuel solution comprising aqueous uranyl sulfate approaching isotopic purity in U-235 and within said preferred concentration range, an amassment of about 11/2 to 2 feet in diameter would be adequate to provide a critical mass, while for uranium of natural isotopic constitution dissolved in -deuterium oxide an amassment of about 35 to 40 feet in diameter or more would bel needed. Toward further minimizing the necessary volurne of the rotating amassment, it is preferred to jacket the amassment in a neutron rellector; several inches or so of an eicient neutron moderant such as graphite, beryllium oxide, beryllium metal, deuterium oxide or water is well suited. Upon thus providing a systemr susceptible to controlled chain fission reaction, it becomes appropriate to interpose a means for controlling the reaction rate--for example, the familiar rods or plates comprised of highly voracious neutrons absorbing materials such as cadmium or boron, adapted to be adjustably inserted into the core for setting and maintaining neutron flux level, and concomitantly rate ofl fissioning, at whatever intensity may be desired. Other features important to eiciency and safety, include the provision of withdrawal means for continuously tapping'evolved gas from the vortex-cavity as it concentrates there, means for separately subjecting the Withdrawn gas to controlled recombination to water and for thereupon returning it to the reactor. core system, and heat-transfer means for extracting useful power generated by the reactor, preferably .compising circulation ofthe VVfuel liquid. through an Y' external heatexchanger. 'if q A lmore' comprehensivega-g-id detailed insightfinto the present method and means is afforded by considerationff the L'specific equipment a'nd operatiol'ls preferred .by aap'- pl'icants. Wh'ilepractice of the present 'nventionjinaci cordancewith theforegoing general outline is notflimited to` any specific design of `neutronic: reactor, the'rreacto Fig. 1 is an overall; a'ssembly'ill'stration of `a'circulati ing'liquid fuelr'eaetor adapte'd toy operation and embody# ing apparatus` in t accordance with the present invention,

together with .electric generating' 4equipment deriving its power therefiornfwhich altogether constitutes an in`Y tegral, self-contained `electricfjgenera'ting' plant..

of 'special core tank arrangements 'for maintaining'the vortexV by 'tangential introduction fofjthe liquid stream; v

specifically;

i YFignl shows a` simple 'core-.tank with the equa! `torial plane.

Fig, 4ishow's internal details and the liquid ilovv pattern ofthe' more complexcore tank employed in the Fig. 1-

Fig. 2' system.' Y s Fig., sets forth an optimum arrangement of optional special bales for promoting advantageous liquid` mixing within the vortex.

inlets in the equatorial plane.' p s Fig. 71is a'n enlargedsectionaldetalloi the piping pene` i tr'ating' the walls of the'surge standpipe Y"member of Vthe p Fig. 1-Fig; 2,-@Fig.`4 system.' l 'p Fig. 82 isv asectional view'fof thefexpansion and pres# ,4o

Surizervvessel surmountin'g' the surge st inthe Fig.

andpipe ,i i Referring4 toztheaolverall reactorpowered electri g'ertf` I eratingpla'nt, Yillustratedjin Figff'l, aisphericligcoretank Y liglpre'ssure-tightfand,adapteda-tocntaigfa.su ercriti'c'al 1'- `amassme'nt of4 an aqueous i highly enriohedv'in; illl-#253 fand. in 'spacedrelationigto,` adaptedxto` draiablyv contain: a-,contentoffdeuterium lution; V2;'jofl uranylt ul disposed central Within,

oxide 4, `um,1ers/ing the "core tanicl; `The rpressure:vessel 3 is providedV with 'a removable; pressuretigiht?lfgasketed cover 5 retanedrsecurely byrnu'ttedf'studaboltsro, 166.'

` Communicating substantially tangentiallyintofthe "side-5"u Ydump lineextension" nally tees into'the vuranium -inhouter pressure 3,"`

sys'temillustrated in theappende'ddrawings, particularly .10

of 'a system" ofya4 multiplicity offU-shaped'uraniunt so Vtion conducting tubes (not shown) Within the-exchanger"- whichwultimately discharges at the tube-side outlet 16,

-necting' piping leads to` the inlet of an integrally-electrically-driven oil-cooled uranium solution centrifugal pumpV 17', Whichgfdischarges into 'a' uranium solution retu'rn pipe 18',whii:h'iritu1`11 leads'back through the `pres- 'sureftight cover 5, and'at its terminus forms said uranium solution'inlet duct 7. Y

`Meanwhile,- theV vgas-liquid: 'discharge tube I 12,'J'afte'r leaving'the Asurge standpipe'Sgis" connected into the tubes-ide of' a` tube-and-shell` econornizer heatlexchanger 19,

' which 'inzturn discharges" through Va' remotely-actuated uranium solution pressure-letdown throttling valve 20, Y

rality'o'f elongated, slenderfhonizontah external-'watercoi1cooled,clo1sed, cylindricaluranium solution storage 22, v22', 22". -Vllrlpwardfx'om the evaporator 21, a vapor line 23, leads into a ywater-cooled vuraniurr'i solution lcondenser 24. kFrom the condensen-a 'condensatedr'ain ,Y line 25, descends to a T 26, where it forks into two w branches, one leading into a pair'of condensatetanks-127, a 27', suspended from a Weighing scale r'system (not` shown), WhileV the other branch leads directly `back to the system of'ura'nium solution storage tanks'ZZ, 22', 22"; the latter branch is provided with a remotely-actuated l. A* valv'e, termed themncentration valve, 28." The system Figure 6 shows a simple core-,tank with a'pluralityiof' of uranium solution storage tanks 22, 22', 22",-drains Vinto a: discharge manifold 29, which is connected byA piping to :the inlet side vof a diaphragm pump 30, actuated -line- 31, Vprovided with. a rernotelyfactuated. valve, termed v t '1 the dilution vajlvet` .32, Whichline `ternu'nates by -teeingv i 'ntoV thepranium solution pipingmle'ading from the dis? barge manifold 29, at the inlet te the diaphragm pump 30,? r

'diaphragm 530, discharges'through the lthezeconomizer heatexchang'er 19,V and' on 5 continuing from `the dump valve 35, av uranium solution of `core tank 1 is a uranium` solution'iiilet7,lwhile from A the top of the core tank, vand in communicationwith the interior thereof, a uranium solution surge standpipe 8,

and leads directly into .the bottoni of .a .pressure-tight 1 expansion. and pressurizer vessel 9, s'urmountedupon V vertically ascends throughthe pressure-tight cover- 5 the upper extremity thereof. Commencing at the upper periphery of the interior of the core tank "1 anddisposed eoncentrically Within,v andinternallyspaced"from, `the ture 11,in `the walljthereo-h` As-'may furtherllbeseen inf Figs. 4 and 7, inside the uranium solution outlet pipe d0,

. an4 even smaller-diameter'ed gas-liquid discharge Vtube'n12;

likewise commences at the periphery of theinte'- `rior of the core tank 1, 'rises 'within the uranium solution l outlet,` pipe through .the coverl 5, 'continues upwardly and passes through the wallloffthfe uranium solutionoutlet itseli Vbends. perpendicularly-Landpasses through'v the: ."wall surge standpipe. 8,`as is; detailed in cross-sectional Figs.` Y 4 and, 7-is' ag'srrialler-di'anieteed uranium:solution` outlet Y pipe 10,; vvhichrises` Within :thestand pip'eiS through the cover 5 and thereupon 'l bends perpendicularlyfto', ,and `65 oxideY 4, i Y f Communicating with the interior, and descending fromk the bottonn', of pressure vessel v3; a'deuteriumoxide outlet fas'oactirigl uranium solutionemergencyldump valve B5;

closed,"tubularthinrbles l36, 3-6, 36", adapted tothe disposition therein of lowerpable control rods 81, 81' (rod hiomfthimble 3,6V not shown'in Figurel) adapted to have fattached at their lower ends platesV comprising cadium'and/or boron (not shown in 'Figure l in the interestyo'f clarity; shown in Figu'revZ), forfmechanically'- drivenv adjustable vin'sertioin"into the bodyfof 'deuteriurn close proximity'of core' tanlcl.`

line 38is 'connected to the inletof an integrally-electri;

cally-driven, oil-cooled' deute1ium, oxide centrifugal pump'f 3.9,: Whichdischarges 'through'the tube-side 'of' la .U-'shaped tube-and-shell deuterium'oxide heat exchanger 40', which'in lturn discharges through a deuterium Voxide y Y return .pipe 93, 'through 'a control rod thimble 36, pipe,I Qgytfhere that,pipe-bends-perpendicularly,ai1d ;tl1en backV into the top of the pressure vessel "3. yTeed from the-deuterium` oxide outletV line 38 a deuterium ,oxide Y V.1M 7S throushf T133; therein, Con- .'ne'cted tothe bottom m A p ation diunpy lineY `34 curves upward, proceeds Vtl1r`oug`,l'1, the

outletnipple 99 leads to a remotely-actuated deuterium oxide pressure-letdown throttling valve 41 from Where a deuterium oxide discharge pipe 100 leads, to a plurality ofI elongated, slender, horizontal, external-water-coilcooled,.closed, cylindrical deuterium oxide storage tanks 42 42', 42"; this tank system drains to the inlet of a deuterium-,oxde diaphragm'pump `43, actuated, again, by a line of Vpulsating hydraulic fluid energized by a remote pulsating piston pumpk (not shown). lThediaphragm pump 43, then discharges into a deuterium-oxide reintroducton pipe 94, teed backinto the deuterium oxide outlet line 38at a point farther down thereon', toward the deuterium oxide centrifugal pump 39. Still farther along the deuterium oxide outlet line 38,- there is teed therefrom a deuterium oxide dump line 44, leading through a remotely-actuated quick-operating deuteriumv-oxide dump valve 45 and connecting into a deuterium oxide vapor manifold 46which lis disposed over and connected into the top of the deuteriurn` oxide storage tank system42, 42', 42", and is provided with a vapor line ascending to a Water-cooled ldeuterium oxide condenser 47; a deuterium oxide condensate drain line 48, is provided for conducting deuterium oxide condensate back into the system of deuterium oxide storage tanks 42, 42', 42". :To pressurize the deuterium oxide 4, in pressure vessel 3, with high-pressure-helium, a remote source (not shown) of high-pressure helium is connected by a helium delivery tube 9,5, through a steam-heated silica-gel absorber 49, andI by a helium delivery tube extension 95', on into control rod thimbles 36, 36', the interiors of which are in vfluid, transmissive communication with the interior of pressure vessel 3.

Enveloping the described, clustered apparatus ,is a radiation shield 5d, comprising a special Barytes-.co'ntaining concrete of several feet thickness, and fabricated of solid concrete `blocks to aord removability,gwith only the outer courses thereof being mortaredg. removable access plugs 5i, 52, 53 are provided in its walls and similarl access plugs (not shown) are provided in its roof. x t Penetrating the shield 59, a boiler feed WaterlV-inlet pipe 54, is connected into the shell-side of the U-shaped deul,

terium oxide heat exchanger 4th; this in turn dischargesthrough a heated-water delivery. 4pipc-96 -nto ;theshell side of the uranium solution;heat;l exchanger. 14;;Pl5'or conducting away thejsteam generated from the boiler feed Water in the uranium solutionfheat exchanger 114,-1a steam line l55, ,connects from the top of the shell-side of the. heat-exchanger i4 intoa steam drum 56, `from which a' steam delivery pipe S7, passes` out aof the shield-S0,l and into connection with theinlet of a steam turbine 5S. The turbine 53 is adapted to drive an alternating-current electric generator 59; both are disposed outsidethe shield 50. Steam from the turbine 53, discharges into a watercooled steam condenser 60,` connected to the hot-Well 6l, of which a hot-well pump `62, is provided'for pumping steam condensate ,into a feed water storage'tank 63, which in turn drains to a boiler feed waterpump 64, which discharges into the aforesaid boiler feed water inlet pipe54. Y

Returning attention to the )gas-liquid discharge tube 12, the system beyond its letdown throttling valve 20: is adapted to afford escape-of; gas .from liquid uranium solution at steam heated evaporator 21, whereupon the gases-predominantly hydrogen and oxygenin stoichiometric proportion for water formation-are adapted to pass off through vapor line 25 to accumulate -in the top of uranium solution condenser 24; For removal and recovery of vgases accumulating there,` a non-condensable-off-gas line connects from the uranium solution condenser 24 into a1gas recombinationY and recovery system comprising, in order: first a llame recombiner 65, containinga spark-gap'passing a continuous electric spark into contact with which the gases are passed for Vcontrolledcombustion of their hydrogen andoxygen content back-into water; second, a catalytic recombiner 66, containing a heated bed of platinum-surfaced catalyst for further recombing any remaining uncombined rwater components; third, a water-cooled off-gas condenser' 67; fourth, aFreon-refrigerated cold-trap 68; and tinally a battery of parallel charcoal absorbers 69, 69' for absorbing any non-condensable radioactive gases, all backed up by avacuum pump discharging into a tall meteorological smdkestack for safe dispersal of any possibly-escaping radioactive gas -to the atmosphere V(neither shown). A

suitable drain line 97, for conducting recombined water back into the uranium solution system, leadsfrom the various components of the recombiner system. Likewise, for recombing any deuterium oxide decomposed into component gases, which would analogously accumulate in thev top of the deuterium oxide condenser 47, a similar deuterium oxide recombiner system, comprising, in order, a deuterium oxide catalytic recombiner 70, a lWatercooled .deuterium oxide off-gas condenser 7l, a Freonrefrigerated deuterium `oxide cold-trap 72, ak pair .of deuterium-oxide-system charcoal absorbers 73, 73 which discharges" through another vacuum pump to the tall smokestack (neither shown), and a suitable deuter-ium oxide drain line '98, for returning recombined deuterium oxide back into the deuterium oxide system, is, provided.

Bridging from removable plugs in 'shield 50, horizontally penetrating through sealed apertures in the'bottom of the pressure vessel 3, and terminating in closed ends just below the bottom of core tank 1,' are several instrument tubes 74, 74' for affording removable insertion' of radiation-measuring instruments (not shown) to the proximity of the Vcore tank 1.

Not shown are thick vertical partition Walls of shielding masonry which compartmentalize the several uranium solution and deuterium oxide circulation loops into respective separate cubicles, to enhance convenience, safety, and radiation-shielding eiectiveness, or a maze of auxiliary Water-cooling piping, sensory instrumentation for temperature, pressure, specific gravity, valve position telltale, and the like, and their telemetering lines, uid lines for fluid-actuated diaphragm-controlledvalves, an4 overall electrical system, apparatus structural supports, emergencyzstandby cooling system, and the like, all of which are inherent, standard engineering fadjuncts to liquidprocessing and heat-power apparatus of the sort illustrated. yv Referring tol-iig. 2, an enlarged and more detailed illustration of the-central coretank-pressure vessel-expansion and pressurizing chamber-control rod thimbles sub-assembly Iof the Pig. 1 reactor is. presented in a partially 'eutawayview.: Adhering to the Fig. 1 reference numeral System, Y with new numbers for further details, 'core tank 1,'disp`osed inthe pressure vessel'3, has tagentially communicating through its side the uranium solution inlet duct 7, which is looped'completely around the surge standpipe 8', to afford ready linear thermal expansion of the duct. In communication with the interior of pressure vessel, 3, and mounted upon the surge standpipe S, is a catalytic recombiner 75, filled with catalyst pellets (not shown) for effecting recombination of decomposed deuterium oxidecomponents directly Within the pressure vessel 3. The surge standpipe 8, rises through -the pressure vessel cover 5, and-into the bottomof expansion and pressurizer chamber 9, which-as is further detailed in cross-sectional Fig. 8-comp`rises simply' a steamheated tube-and-shell heater portion 76, with steam inlet 77, and steam condensateoutlet 78, directly surmounted byja vapor dome portion 79, having connected into its top a non-condensable-gas bleed Vent 80. symmetrically surrounding thel expansion and pressurizer chamber v9, are lthe three vertical, cylindrical, closed-top control rod thimbles 36, 36', 36", communicating with the interior of pressure vessel 3. Adjustably suspended from within are control rods 81, 81', 81", having aiiixed at their lower extremities, respectively, a'regulating shim plate' 82, cornprising highly-neutron-absorptivecadmium and/ or boron',

Yrod thimble 36', raising and lowering, as desired, of

the control rod l81' therein is effected by an internal electric motor 84, driving a gear train 35, essentially rotating Aa nut` on a non-rotating, vertical, threadedrrod 86, the lower extremity of `which rod has affixed thereto an electro-magnet 87, which attracts and thus releasably holds the top 102 of the controly rod 81'. The electrical leads 88, ofthe electromagnet 87 are coiled spring-like within the thimble to provide ready extensibility. VWater'- cooled jacketing 89, is provided to cool the lower portion of each thimble to reducethetemperatures to which the electrical equipment is exposed. The internal construction and arrangements of each of the lother two thimbles .36, 36, not shown cut away, are substantially identical with that of the thimble 36?, shown cut away. for introducing fluids'into the pressure vessel 3, through theA control rod thimbles 36, 36', `a helium inlet line 90, and a deuterium oxide inlet pipe 91, are teed into thehthimbles.;

Having pressure fittings ready for connection with further piping are the uranium solution outlet pipe 10, the gasliquid discharge tube 12, and the uranium solution dump line 34, as is the line leading to the T 33as further detailed in cross-sectional Fig. 7,-in the-surge standpipe 8, for the introduction of make-upuranium solution. Spaced slightly from the interior walls of the pressure vesselV 3, is a unitary How liner 92, to direct the flow of incoming deuterium oxide irst along the walls of the pressure vessel 3, to assure its adequate cooling. From thebase of the pressure vessel 3, project deuterium oxide outlet line 38, and instrument tubes 74,1 74'. v

In the operation, in accordance with the present invention, of `the overall system shown in Fig. ,1' and as enlarged in part i'n Figs;` 2, 7, and l8.a continuous stream of an aqueous Y, solution 2, of T uranyl sulfate highly isotopically 'enrich -in U-235, is vigorously` injected, through uranium solution inlet dutf'f, tan'gentiallyv i'nto theinterior of the core tank 1, wherein` it produces rapid rotation of the contained solution, establishing a vertical tion products; in accordance with ,the present invention, the evolved gases centripetally migrate rapidly to the' axial cavity of the vortex, from which they are continuously discharged, together with va relatively small portion of I uranium solution etiluent from the core, through gash4 liquid discharge tube 12.- Discharge through gas-liquid discharge tube 12,- is effected suiciently rapidly that the gas-,tilled vortex-cavity'is maintained at all times slimmer Y than the mouth jof the gas-liquid discharge tube 12 with which' it registers, such that the cavity does not undesirably discharge gases `into the uranium solution outlet pipe 10. .From the gas-liquid discharge tube, the

solution-gasmixture is then passed through the economizer-heat exchanger 19, to be cooled, and through uranium solution pressure-letdown throttling valve' 20 to be throttled down to a pressure of'` only about 5 pounds per square inch, and` on to the steaml heated evaporator 21,

where' the solution kis partially evaporated. The gas,

vortex therein. The uranium solution 2,v llsthe surge i standpipe 8, and further partially' lil-ls the expansion and vpressurizer chamber 9, on'vup through its steam heater portion 76; there ther heater 76,1 heats the local solution to 285 C. which continues :to vaporize into the pressurizer vapor dome portion 79, Vuntil' the equilibrium vapor pressure at that temperature of 1000 pounds per square inch is attained,which-pressure `is, Vhydraulically core tank to 250 C. The heated uranium solution axiallyY leaves the core tank 1, through the -annulus formedf betweenv the uranium solution outlet pipe 10, and the gas- Y liquid discharge tube 12 concentrically disposed therein,

and passes. through the tube-side, of the uranium solution heatexchangerld, there givingup its -heat to, and

i i boiling, the boiler feed water in the shell-side thereof,

Ytogether with evaporated water vapor,'leaves through the vapor line 23, and passes to the uranium solution condenser 24, while theevaporators distilland drains into the uranium solution storage tanksystem 22, 22 22".; atthe condenser 24, thewater vapor is condensed, While the evolved gaseous decomposition products of' water accumulate at the t'op Vof'the condenser, andare continuously withdrawn and passed through the llame recombiner 65catalytic-recombiner `66, off-gas condenser 67, and liquid Freon cold-trap 68, to berecombined,v condensed, and returned through theV uranium solution `drain line 97, on into a uranium solution storage tank` V22 and thus tothe uranium 'solution systemj non-'recorri-V binable, non-condensable gases, comprising predominantly gaseous fission product-species, arethenlargely absorbed in the battery of charcoalabsorbers 69, 69. Thefconportions of the branchingA depending on the isetting of the-concentration valve.l 28, lUranium solution is con.v ftinuouslypumped from; the system of uranium solution storage tanks 22, 22', 22", by tlie uranium solution diaphragm pumpY 30, with the ongoing solution therebe- ,coming more or less diluted with Water from thecorl`l densate tanks,27, 27', dependingron the setting of theY dilution valve `32 leading from the condensateetanks 27, 27"` Froni-thef'pump'30,theuraniun1 solution is dischargedl through the shellV side ofthe economizer heat exchanger 19, to be reheated, from where it is' routed through`T, '33,' back through the surge standpipe 8, to the coretanl( 1. The'foregoing'operation of continuous partial distillation'of the uranium solution and adjusted storageof the condensate in tanks for release through the dilution valve is particularly important in that it Vcontrols the precise concentration of the ongoing stream of uranium solution being pumped through the core.

and from there passes through the uranium solution i centrifugal pump 17, which discharges it back Athrough w the `uranium solution t return piper 18, to` the 'uranium solution inlet duct 7,and thus maintains vigorous circulation of uranium solution through such loop. v Meanwhile, within theV coretank, thev radiation of Athe fission reaction continuously induces considerable water decomposition with copious 'evolution of gaseous decomposi- 'Ihat is, on partially evaporating the uranium solution in evaporator 21, substantially plain water is continuouslyl distilled off through vapor line 23, leaving a distilland closing the concentration valve 28, withy dilution valvel i' 32.stillclosed, the. distillate is'routed lto be retained in the condensatetanks27, 27', and thus is restrained from returning tothe tank system 22, 22', 22", resulting ina pr'Q-,grssive increase Vin ithe concentration of the uranium y solution being -circulatedthrough-'the core* tank. VU'pjon later reopening the concentration valve 28:,the uranium thereupon, the ongoinglsolutionmay be rediluted as de`- sired by judicious opening of the dilution valve 32, with concentration valve 28 remaining open, thereby gradually draining condensed water into the outgoing uranium solution. Simply, therefore, the term concentration valve reflects the function of the valve 28, in serving to concentrate the circulating uranium solution upon its being closed from its normal open position, while the term dilution valve reflects the function of the valve 32, in serving to dilute the circulating uranium solution upon its being opened from-its normally closed position. Since the condensate tanksare suspended from weighing scale means, the weight of condensate in the condensate tanks '27, 27' is readily determined to indicate the concentration of uranium sulfate in the remainder of the system at any given time. Such solution concentration adjustvment is particularly significant here because the degree of reactivity of the` solution in the fission reaction is sharply dependent upon the preciseV concentration of uranium solution in the core tank 1. Accordingly, remote manual adjustment--or, more conveniently, continuous automatic adjustmentof the settings of the concentration valve 28, and dilution valve 32, in response to the rate of fission in the coreV as indicated by radiation detection instrumentation disposed in instrument tubes 74, 74', while continuously circulating uranium solution through the core-evaporator-condensate-tank loop, is employed as the primary means for regulating the rate of iissionreaction in the core in this reactor.

The uranium solution dump line 34, passing from the bottom of core tank 1 and closed by the uranium solution remotely-actuated quick-opening dump valve 35 affords rapid emergency emptying of the contents of the core directly to the system of uranium solution storage vtanks 22, 22', 22; the storage tanks 22, 22', 22" are maintained at a pressure about a thousand pounds per square inch lower than that in the core tank 1, so as to effect hasty removal,` and are of a `quite-small-girthed elongated coniiguration--a geometry which precludes the iissionable fuel solution contents thereof from ever attaining criticality.

Pressure. vessel 3, is maintained partially filled, norvrnallyto such a level .as to keep the core tank 1, completely submerged, with deuterium oxide 4, which, in -forming'a vca'. one foot thick jacket around the core tank 1, serves as a neutron-reflector for economizing neutrons -in the chain reaction obtaining'therewith. The portion of pressure vessel 3, above the deuterium Voxide surface is maintained filled Vwith helium at substantially 1020 .p.s.i., a pressure slightly' greater than that of the uranium solution inthe core, such that upon any ruptuure of the core tank 1, all leakage will be inward, to avoid hazardous effusion of the iissionable material. The helium is delivered, from a remote high-pressure source, through the steam-heated silica gel absorber 49, for purifying the helium, and through helium inlet line 90, leading to the pressure vessel 3, through control rod thimbles 36, 36', thus pressurizing the deuterium oxide system. In operation, the deuterium oxide 4, in the pressure vessel 3, becomes progressively heated, through its contact with the hot core tank 1, through its attenuative reaction with neutrons emanating into it, and through its contact with vessel through overheating. The deuterium oxide in the the walls of the pressure vessel 3, which also become heated as the result of attenuative recation with neutrons and gamma rays. To dissipate such-heat, the deuterium ,oxide is continuously circulated out of the pressure vessel through the deuterium oxide outlet line 38, then through ,the deuterium oxide centrifugal Lpump 39,y which maintains the circulation, thereupon through the tube-side of the deuteriumoxide heat exchanger 40, where the heat is transferred to the stream of boiler feed water flowing through the shell-side-'of--the exchanger, and finallyv back into the pressure vessel 3;A Imre-entering the pressure vessel 3, the deuterium oxide iiow is directed first against the inner walls of the pressure vessel by the flow liner .92, so as to avoid any impairment, of the strength of the pressure vesselr3, is also subjected to intense ionizing radiation from the chain-reacting amassment in core tank 1, and-consequently likewise suffers considerable decomposition into gaseous components. While the catalytic recombiner 75, mounted directly within pressure vessel 3, is normally eective in recombining decomposed `deuterium oxide to a large measure, quite complete removal is insured by continuously discharging a portion of the circulating deuterium oxide stream from the deuterium oxide outlet line 38, through the deuterium oxide pressure-letdown throttling valve 41, into the system of deuterium oxide storage tanks 42, 42', 42", which are maintained near atmospheric pressure. The gaseous decomposition products, along with any deuterium oxide vapor, pass to thedeuterium oxide condenser 47, from where, after condensation of the deterium oxide vapor, the gases are Withdrawn through the deuterium oxide catalytic recombiner 70, the `deuterium oxide off-gas condenser 71, and the deuterium oxide cold-trap 72, where recovery by recombination and condensation of most all of the decomposed deuterium oxide is effected; finally, 'remaining non-condensable, non-recombinable radioactive gases are trapped in the deuterium oxide charcoal absorbers 73, 73', while any gases not trapped are meteorologically disposed to the atmosphere by discharge through the deuterium oxide vacuum pump to the tall smokestack. To replace the deuterium oxide continuously removed from the deuterium oxide outlet line 38, -the deuterium oxide diaphargm pump 43, is employed vto continuously pump deuterium oxide from the storage tank system 42, 42', 42", back into the outlet line 38.

It is particularly significant here that by adjusting the 'setting of deuterium oxide pressure-letdown throttling valve 41, the relative rate of deuterium oxide discharge lfrom the outlet line 38 may be made greater than, equal to, or less than, the rate of continuous deuterium oxide replacement by diaphragm pump 43; in this way the deuterium oxide liquid level in the pressure vessel, 3,

may be rapidly varied and precisely lixed at any desired height. Since the degree of reactivity of the chain reacting amassment in the core tank 1, is directly dependent upon the neutron reflecting agency of its enveloping bath of deuterium oxide, decreasing the level of the deuterium `oxide reector `4 and the degree of submergency therein of the core tank 1, has a pronounced eflect in correspondlingly decreasing reactivity of the amassment within the corre tank. Therefore, remote manual-or, more conveniently, automatic-adjustment of the setting of the deuterium oxide throttling valve 41, again in response to the rate of fission reaction within the core tank 1, is

` terium oxide'storage tanks 42, 42' 42"; again, the fact that the storage tank system, 42, 42', 42", is normally maintained at a pressure of almost 17000 pounds per square inch below that in the pressure vessel 3, promotes rapid emptying, and the quite-small-girthed, elongated configuration of the storage tanks geometricallypreclude the attainment of a critical mass therewithin, even if the Acore tank were misfortunately to rupture and discharge its content of uranyl sulfate into the deuterium oxide system.

In the operation of the control rods 81, 81', 81, safety plates k83, 83' are normally retained at their uppermost vpoint of travel, away from the core tank 1, while the -regulating shim plate 82 vis usually maintained partially .lowered into the vicinity of the core tank 1. The cadmium and/or boron in the regulating plate 82, voraciously yabsorbs neutrons which would otherwise be reflected back into the chain reacting amassment in the core tank,

antenna and thus alters the degr'eeofreactivity of the amassment;

as desired through the drive means-ie., electric motor 84, gear train'85, and threaded drive rod 86, in control rod thimble 36', and substantially *identical apparatus and arrangement (not shown) in the other two control forni of the -ssionable material to be employed. ver

rod thimbles 36, .36"-is eifected yto roughly regulate the overall rate of ssion in the reactor, .especially in operation at very low power levels. Safety plates 83, 83 contain `suiiicient cadmiumtorender theamassment subcritical upon being lowered to Atheir 7lowest point of travel immediately adjacent core tank '11; `and may be 'lowered `by their electric motor gear train to shut down the retromagnet for abrupt shutdown is elec-tible, both manual-V ly, and automatically by means responsive to excessive reaction rates through theagency Vof radiation-,detection instrumentalities disposedlinftheinstrument .tubes 74, 74.

"Subsequently, the dropjgteldregulatingV and .safety plates may be re-elevated by lowering the electromagnets until they contact the upper extremities of the control rods, whence re-energizing `the electromagnets .eifects recoupling. t

the-operational range, :the thermal stability ofthe sulfate salt is definitely assured; the phase diagram of the uranyl- Vsulfatewater system has been determined upto the critical point, and the system Vis found to remain homogenous at all concentrations up to '294 C. Also, notable radiation stability is exhibited; in aqueous solution, uranyl sulfate remained clear and unprecipitated upon irradiation in 4an operating neutronic reactor at a neutron ux of 5 1011 -neutron/cm.2/sec. for so long as 2900 hours, thus giving indication ofretaining radiation-stability indefinitely, although its aqueous solvent, of course, suiers considerable decomposition into its component gases. Advantageously, the sulfur'atoms incidentally introduced have a neutron absorption cross-'section so low as 0,4 barn, and hence are practically innocuous from'a neutron absorption standpoint. Aqueous -uranyl sulfate, however, is seriously corrosive to metals -of construction; the problemis Ydoubly deleterious sincejthe corrosive action depletes the `solution of sulfate ions, leading to the progressive precipitation of uranyl oxide, which represents hazardous accumulation of iissionable material as a .highly-concentrated precipitate. However, stainless steel,

v. especially No. 347, and zirconium have demonstrated The short and direct connection of thecore'tank 1, to

densationto avoidinterterence inthis condensation mechanism, vapors are constantly bled from the top of the dome through gas bleed vent $80, to avoidaccumulation of non-condensable gas therein. Within the vapor dome 79, a sensor .ltill-diagnammed in Fig. S--comprising buoyant chamber and variable inductance transmitter telemeters indication of the `precise lliquid level in the pressurizer 9, in response to .which the setting of the re- 1notely-actuated uranium "solution let-down throttling valve 28, is automatically adjusted so 4as to maintain a constant liquid level inthe 'pressurizen For deriving useful power Jfrom thereactor in this systern, boiler feed water is pumped from yfeed water storage tanks 63, by boilerfeedwater pump 64, via the boiler feed water inlet ypipe 54, through the shield S0 and through the shell-side the deuterium oxide heat exchanger 40,

where it is partially heated by the deuterium oxide. i

Thereupon, the heated feed water proceeds Vthrough the shell-side of the `uranium solution "heat exchanger 14, wherein, in contactwith .VU-shaped .tubes Vfilled with circulating uranium solution at ca.250 C., the Water boils; resulting steam proceeds away through steam line 55, and accumulates in the steam drum 56. From there, the steam, upon directly leaving ltlie shield through lsteam delivery pipe 57, is passed into .the steam turbine 58, to empower the same, which in turn `drives the alternating current electric generator 59, thereby producing the end productelectric power-of the entire plant.` Finally, the 'steam turbine 58, is backed by 1a conventionalfwatercooled steam condensertl; the condensed water accumulating in the hot well 61, of which is returned by hot well pump 62, to feed water-storage tank -63, for reuse as boiler feed water. i Y Y Considering, more particularly, :the special aspects and incorporated reiinements Ain the Yreactor system illustrated in Figs. l and 2, uranyl sulfate has been found to 4possess staunch resistance to such corrosion; their use for all surfaces in` contact with the lsulfate `has proven to largely'obviate the dinculty. Among v`other applicable `soluble com- 'pounds `of ti'ssionable material, ,uranyl nitrate exhibits good radiation stability andlow propensity for .neutron capture, .but is subject to serious hydrolytic decomposition above about 17 5 C. wherein it evolves gaseous oxides 'of nitrogen in aggravation of the bubblingfdiiculties; ac-

cordingly, while aqueous uranyl nitrate is applicable below this temperature, it is rather unsuitablejfor the higher power generation rates. In `the `case of uranyl uoride, although the iluorine atom is `acceptable from a low neutron absorption standpoint, and the compound has been found thermally stable in general, although engaging in some hydrolysis to exert Va hydrogen iiuoride vapor pressure, up to 250 C., it exhibits inordinate c-ol'rosivenessa detractive practical shortcoming.

Normal Water is pre-eminent as the liquid moderarnt;

deuterium Voxide could also be effectivelyyused, butnormal water has a considerably shorter Yslowing down, length for neutrons, so aiords a smaller reactor core. Similarly for the reflector, natural water or else a solid such as beryllium, beryllium oxide, or graphiteV is suitable, while deuterium oxide is particularly Vpreferred in that itis a drainable liquid aording enhanced mechanical convenience and safety, and that it has a neutron absorption crosssection per molecule (03:0.0009 barn) lower by ca. three `orders of magnitude than that of natural Water (0:0L69 barn) but a neutron scattering cross-section per molecule (as=l5.4 barns) lower -by only a factor of six than that of natural water (as=94.l barns), `and consequently is characterized by a commensurately greater ratio of' t aa representing superior reectant quality. g

An unusual and especially signiiicant attribute of the illustrated reactor system for practical application `is that it is inherently self-controlling with respect to reaction .rate so las to minimize spurious changes in rate o f react-ion. The liquid fuel system will vthermodynamic-ally compen- Vsate for, and uneventfully .adapt itself to accommodate v instant reactor system; that-is, the degree of chainvreac- .tivity of the reactor varies yto an unusually v1g ro11ounced eminent 4attributes especially lfavoringitsselectionasY the 1,75 degree Villversly i0 AChanges =i1i the mperaul' 0f the `corresponding liquid expansion; since the volume. of the core tank is xed, such expansion results in the displacement of a commensurate proportion of the fuel solutions from the core, and the consequent decrease in fissionable material content of the core serves to lessen the degree of chain reactivity of the amassment. Therefore, since the temperature of the fuel solution responds directly and virtually instantaneously to the rate of chain reaction, and since -a surge standpipe and an expansion chamber of ample proportions are immediately aiiiliated with the core tank to permit unimpeded expansion of fuel solution from the core, any incipient upward excursion of reaction rate is immediately checked by the ensuing expansion and decrease in reactivity. As a result, the system is strongly resistive to alteration in reaction rate, and automatically counteracts and controls propensities toward increases in reactivity Iand rate of reaction much more potent than those which would completely destroy most other types of reactors. Consequently, the usual need for complicated, `failure-proof, constantly-acting, highspeed control mechanism is avoided, while a reactor system of inherent safety eminently suited for common power plant practice is afforded. In addition, a general lautomatic response of reactor operation level to fluctuations in the demand of electric power and hence turbine steam is realized; increase in the rate of steam discharge to the turbine is accompanied by an increase in introduction of boiler feed Water to the uranium solution heat exchanger 14, the resulting greater rate of cooling of the uranium solution tends to reduce the mean temperature of the fuel solution in the core, hence to increase its density, in turn to increase itsssionable material content, and thus to increase the rate of fission reaction, thereby tending to provide the additional thermal power demanded in the form of a considerable increased production of steam of somewhat lower temperature.

Extraordinarily, three independent means are provided for adjusting the rate of ssion in order to insure continued positive regulation of the reaction. First, delicate regulation in reaction rate is made by adjusting the precise concentration of fissionable material in the circulating fuel solution, particularly through continuous distillation of aqueous solvent from the circulating uranium solution, and through the described operation of the concentration valve 28, and dilution valve 32, releasing into the oncoming stream at adjusted relative rates separately accumulated concentrated uranium solution and water appropriate for establishing the desired concentration. Response to this regulating means is generally rapid and oscillations of reaction rate around the desired level are quickly damped out, by virtue of the fact that ca. 75% of-all uranium solution involved is within the core at any one time. Second, a coarser general regulation of reaction rate is eifectible by ladjustment of the depth of deuterium oxide neutron reliector covering the top of the core tank, through varying the setting of the deuterium oxide throttling valve 41. Finally, the third separate regulation means, largely for use in starting up and shutting down reactor operation, especially for emergency shutdown, resides in the vertically-movable regulating shim plate 82 and safety plates 83, 83', which afford insertion of suicient quantities of highly-neutron-absorptive cadmium and/ or boron in the proximity of the core, to render the amassment immediately sub-critical.

Por a reactor system having general configuration and proportions as delineated in Fig. 2, the degree of eiectiveness of each of the three separate regulation means, and other variations in operating conditions, with respect to the decrease in the number of neutrons from one successive generation to the next in the chain reaction which is eifectible by each means, is set forth in Table I below.

'20 v TABLE I EFFECT OF REGULATING MEANS AND VARIATIONS IN OPERATING CONDITIONS ON REACTIVITY Akctfl kaft Control Means vReflector Remov Uranium Solution Concentration Adjustment (Aqueous UOz(S1O4)g at 30 gms. UNS/liter).

1.05% per gm. Um/liter. 5%

Control Plates (Full Insertion):

Regulating Shim Plate Safety Plates (ea-ch fixture). Total V 0.17% per o.

0.1% Maximum.

'1 ksrf=elective multiplication factor=statistical number of neutrons generated by fission in one generation per each neutron generated in the preceding generation-in other words, the number of neutrons actually completing the cycle of deceleration, thermal diffusion in core, capture by fissionable material, and sslon, per one starting from fission.

Ic=multiplication faetor=the kcff which would obtain if the particularcore were extended to infinite size, so as to avoid the permanent escape ol neutrons which occurs from a core of finite size.

Akn=change in lcsff produced by indicated adjustment of conditions.

The marked effect of reflector removal in decreasing reactivity is readily apparent; the extent of this effect in terms of the greater quantity of Uzi15 required to consti- `tute a critical mass in the Vabsence of the reflector is further demonstrated in Table II below.

TABLE II EFFECT* OF REFLECTOR REMOVAL AND CORE COOLING ON QUANTITY OF Um REQUIRED FOR CRITICALITY 1 In 18" diameter spherical vortex with slender central cavity.

In operation, the concentration of the uranyl sulfate solution is maintained within the aforesaid preferred range, sufficient deuterium oxide reflector is provided to fully immerse the core tank, and a sufficient degree of elevation of the regulating shim plate and complete elevvation of the safety plates are maintained so as to establish criticality of the amassment and an equilibrium chain fission reaction proceeding at the desired reaction rate. For moderately increasing or decreasing the level of fission reaction rate, the uranium solution concentration is appropriately increased or decreased; for more extensive alteration of reaction rate, coarse adjustment of the general range of reaction rate by changing the depth of reflector and/or the elevation of the regulating shim plate, followed by' fine adjustment by varying the uranium solution concentration, is in order. Upon shutdown of the reactor, reflector shim plate 82 and safety plates 83, 83', are fully inserted to their lowest positions, the deuterium oxide reflector 4 is completely drained from the pressure vessel 3, the uranium solution is diluted with the entire contents of the condensate tank 27, 27', and in addition all of the uranium solution is removed from the core tank to the system of uranium solution storage tanks 22, 22', 222, through dump line 34, and dump valve 35. For a panic shutdown in an emergency, first the regulating shim plate and the safety plates are immediately released and dropped by de-energization of their retaining electromagnets; the 1.22%

Akerl' Y kefr solution`I theboilerfeed water in the uranium solution heat exchangerrapidly ,-increases'the density of the circu-V lating fuelliquid and concomitantly the total amount of proportions, into contact with a spark maintained to'ini duce Vtheir combustion, under controlled conditions, hack to water. As therarriving gases are normally accompanied ssionable material in the coretank, to the end 'thatV enough riissionable fmate'rial would be progressively amassed to. again attain criticality-despite the presence ofthe llowered `'reg'lvil-atng and i safety plateswhereupon fission `reaction would recommence, all frequently in less than nair'ninute.` `Ythilfethis interval ofSub-criticality may well. be'considerablyprotracted by immediately cutting olf any ftlrtherY introduction of boiler feed' water or re movalf'of steam "the uranium solution heat exchanger, `so asf to'fminimize the uranium solution cooling rate, 'neverthele'sslin any case' the standard procedureis` to immediately drainthe deuterium oxide reflector so as tain reaction, such that thelnal equilibrium effect of the plate lowering or raisngis merely to decrease or increase, respectively, the temperature attained in the reaction, with little effect upon the rate of power generation by the reactor. n n n When employing stainless steel apparatus, especially for long time operation' at high temperatures, it is highly advisable that positive steps be taken toward minimizing thedeleterious effects of the corrosiveness of aqueous uranyly sulfate. ASuch corrosion, invariably accompanied by reduction of the uranium to tetravalent state leading to ultimate precipitation of all the uranium as oxide, may be largely overcome by pre-treating the stainless steel by contacting with a strong oxidant so as to form, apparently, an oxide coating thereon. ,For,this, circulating either 1% HNOa or 2% chromic acid through 4the apparatus atA 250 C. for from 4 to 24 hours has proven eminently ecacious. For maximum eiectiveness, periodic repetition of such'treatment, say every month or so, is advantageous. While the resulting corrosion resistance is -not appreciably disturbed by mechanical abrasion, it tends to deteriorate under prolonged intense irradiation, as` evidenced by progressively more pronounced `uranium precipitation; In such case, it is effective to preserve'vthe stability `of the oxide coating under irradiation by incorporating a small amountof nitric acid, say to 1%, or other effective strong `oxidant not otherwise interferent, in the circulating fuel liquid, although' maintaining oxygen gas dissolved intheuranium solution at a concentration of the order of 20 to 100 parts per million is much less contributive to corrosive action and is the particularly preferredtechnique. Such concentration of dissolved oxygen mayreadily be provided by gradual addition of oxygen gas to the stream of `uranium solution being vreturned from the uranium solution diaphragm pump30, and

proceeding tothe T 33,in the surge standpipe 8. In a new installation, initial pre-treatment of the stainless steel with ca. 0.1 M HCl-'-HgNO3 to remove grease and dirt, fol lowed by a purifying wash of4 50 hours with distilled water, is in order. In the Vreflector system, deuterium oxide is much less corrosive such that carbon steel is satisfactory as the reector-containing pressure vessel; while deuterium peroxide promotes slight corrosion, this may be virtually completely inhibited with conventional agents, such as about 0.01 molar trisodium phosphate incorporated itt the deuterium oxide bath.

` In `effecting recombination of the radiation-induced gaseous decomposition products of water, the operation yof the tlamefrecombiner involves simply passing the gases,

comprising mostlyhydrogen and oxygen in stoichiometric by considerable steam,`volumetric proportions of gases` in the steam must be maintained above the minimum required for combustibility; such minimum proportions, determined for various low temperatures and pressures, and alsoinvthe presence of a preponderant partial pressure of h elium as is encountered in deuterium oxide decomposition products, are tabulated in Table III below.

" TABLEfIII -MINIMUM PRoPoR'rroNs FOR COMBUSTIBILITY IN HT-Oq-He-STEAM ADMIXTURES Y [H2 and O3 presented in stoichiometrieproportions] Y Y Volumetric Proportions for Y Total Combustibility Temperature C.) Pressure Y (p.s.i.a.)

Minimum Percent Percent Percent He 2 H2O Hari-02 1 Y 19.06 22 0 78 29. 3 22 0 78 85.0 25 0 75 158 27 0 73 199 27 0 73 262 27 0 73 661 24 0 76 952 15 80 5 965 l5 72 13 950 l5 64 21 l, 018 19 29 52 l Minimum necessary for eombnstibility upon spark discharge in 1050 ml., 3% in. diam. bomb.

2 Snteient helium incorporated to impose a total pressure approximating 1000 p.s.i.a. at the particular temperature.

Y To prevent ash-back of the explosion through the oncomingvapor line, the vapor best be first passed through a bank Vof orijces or nozzles, for example a closed-end metal tube of 5% inch diameter perforated by 50-150 1/32 inch diameter holes, through which the steam-gas mixture jetsat a velocity exceeding the ash-back velocity-generally about 13 feetper second at minimumbefore encountering the spark. In addition, automatic ash back protection may be provided, if desired, by initially adrnixing excess steam with the gas sucient to reduce the gas proportion below the combustibility minimum, and then providing a condenser to remove the excess steam just ahead of the flame recombinen'this precludes flame propagation any further back than the pro- Y vided condenser. For the catalytic recombiner, eminent and satisfactory results have been realized with both carbon-base and alumina-base platinum catalysts.l Preferably, though, a bed, maintained above 500 F. and better at ca. 750 F., of 1/8- inch lby ls inch cylindrical pellets of charcoal or activated alumina on which platinum has k been deposited to a platinum content of the order of 0.3%

to 1% is electively employed.

Removal of ssion products, and addition of make up uranium, should not be necessary for some time after commencement of initial operation, since the rate of U235 consumption andV corresponding formation of fission products is only of the order of 0.001 Vgram per' kilowatt-day of operation.V However, upon attaining a concentration of fission products equal to about 1% of the lissionable material present, further increase in fission product concentration should be curbed by then commencing chemical processing of the fuel solution to remove lission products and plutonium. Conveniently, a

Vproduct and plutonium values therefrom. Particularly preferred `for this, for example, is a highly-developed con# tinuous solvent extraction process comprising substantialasuma 2:3 1y acidifying the aqueous. uranium solutionwithy nitric acid, thereupon contacting with a liquid organic extractant comprising tributyl phosphate diluted with a hydrocarbon approximatingV kerosene to about l5-30% by volume, to thereby preferentially extract virtually all plutonium and` uranium values from the iission-product-retaining aqueous solution, followed by preferentially stripping the extracted plutonium with an aqueous nitric acid solution containing a fewhundredths molar ferrous sulfamate.,V and finally stripping the decontaminated uranium with plain water for subsequent reconstitution as uranyl sulfate and return to the reactor-as is describedl in greater detail in a copending application of the common assignee: S.N. 303,691, filed August 1l, 1952, in the names of T. C. Runion, W. B. Lanham, and C. V. Ellison, for Process for Segregation of Plutonium, Uranium, and Fission Product Values.

Alternatively, the uranium solution may be percolated through a bed of cation exchange absorbent for preferential removal of plutonium values and of rare earth, strontium, cesium, and zirconium iission product species, and theny through a bed of anion-exchange adsorbent for the preferential removal of anionic molybdenum, iodine, tellurium, and ruthenium fission products species-likewise conventional in the art.

Too, over protracted periods of operation, occasional reprocessing of the deuten'um oxide reiiector is beneficial for eliminating undesirable corrosion-product metal-ion contamination; simple distillation is satisfactory.

Returning attention to the remaining four iigures (Figs. 3, 4, 5, 6), and considering especially the particular core tank configurations for establishing the essential vortex, l1Eig. 3 diagrams one of the simplest arrangements for producing and maintaining the vortex by means of introduction of the stream of ssionable material solution tangentially into the core compartment, while separately discharging solution and accumulated gases axially therefrom. Referring to Fig. 3, a spherical core tank 300, has connected thereto alt its north pole, and communicating with the interior thereof, a vertical surge standpipe 301, which, in turn, has eoncentrically disposed therein and terminating at the periphery of the interior of the tank, a liquid discharge pipe 302, and a smaller gas discharge tube '303. In the equatorial plane of the spherical core tank, a liquid inlet duct 304 leads substantially tangentially to the interior of the tank. Connected at the south, pole, a liquid drain pipe 305 leads from the tank. The tank is filled with an aqueous fissionable material solution 306, except for a central, gas-lled cavity 307, which forms in oper-ation and aligns itself with the polar axis and registers with the end of the gas outlet tube 303, upon continuous and rapid introduction .of a stream of the ssionable material solution through :the inlet duct 304. Solution introduction in the equatorial plane, in this manner, has been found ideally adapted to establishing a rm and stable vortex having a cavity which assumes a steady alignment with the axial gas outlet orifice. However, experimentation has revealed that the exact alignment of the axis of the vortex, and with it the central cavity, is governed principally by the position of the liquid outlet from the sphere; with a polar liquid outlet, the vortex produced by location of the tangential yinlet anywhere from 45 north latitude through 45 south latitude will still be precisely aligned with the polar axis. Moreover, even tilting the angle of tangential yintroduction to 45 north or south of the perpendicular to the line of the longitude of the point of introduction, has shown not to disturb the polar alignment of the vortex.

Beneficially making use of such ndings is the refined and particularly preferred core arrangement of the Fig. l-Fig 2 system diagrammed in Fig. 4. Referring to IFig. 4, the core tank 1, is again precisely spherical, and, as in Fig. 3, is provided at its north pole with a concentric nesting of a surge standpipe 8, a liquid discharge pipe 10, and

Z4. a gas-liquid discharge tube 12: r Here,though,pthe surge standpipe is provided at its base with an ample are 404,

and is smoothly rounded at its juncture with the corev tank; likewise the liquid discharge pipe includes a smooth-v ly rounded llare 4,05. at its extremityf rEhe gas-liquid disf' charge tube is provided with a y broad;1 hemispherieal, centrally-apertured nose 406, at its extremity, and integral liquid straighteningvanes 407, adapted to curb continued.

rotation of I liquid Nin the liquddischarge pipe after its. egress from, the core tank. The` tangential liquid inlet duct 7, is inthis,instancelocatedlatca. 45 northlatitude, and is aimed with about a 30' southerly tilt' with respectv t0 a perpendicular to the line of the 1Q11situdecf,jthe

point. 0f. introduction- Again., a liquid drain, Pille( 334v it provided at the south pole,V and avvorteX; cavity 410 formed inl operation, aligns with the polar axis andy registers with. the extrrnityV of, the gasrliqudl discharge tube- 12,k at the aperturein` its nose 40,6, superimposed' through much of the Southern Hemisphere, to. promote,

continual mixingof liquid within the core, and to dispel deleterious relativestagnation, while` sti-ll maintaining a steady vortex aligned with the polar axis. The ared and smoothed edges at the north pole, orices coincide, with the lines of liquid flow. and serve. to. mitigate any, tur-- bulencefin the vortex that the outlets. might induce. With the broad nose 406, of the extremity of the gasfliquid discharge tube, minor excursions of the vortexv cavityv from normal polarv alignment. are tolerated without `adv verse loss of any separated gases into the liquid discharge pipe 10; in practice, the vortex axis tends to precess slight- 1y, whereupon the extremity of the cavity merely dwells momentarily upon the facade of the nosebefore rcturnv ing to its normal registry with the orifice of the gas-liquid discharge tube. The straightening vanes `407, by4 convertingV liquid rotational motion within the liquid discharge pipe into axial ow, serve to salvage kinetic energy and thereby to reduce the pressure drop required tomaintainr the vortex. With such a spherical core tank of 18 inches diameter, operated at a, solution ilow rate of 1,00 gallons per minute, the pressure, drop4 acrossthe tank is only 15 p.s.i., and the afforded centrifugal force ranges from two times normal gravity at the equatorialperiphery to times gravity adjacent the central cavity. In a tission` reaction therein Iat ca. 1000 kilowatts power level, gas evolution proceeds at a rate of ca. 400cc. saturated gas -at operating temperature and pressure per second; since the flowing solution bccomesconsiderably supersaturated in dissolvedA gas, gas bubbles form and grow to separable size veryV rapidly, and are thereupon centrifugally forced to the cavity lin a converging spiral flow path within the vortex, with an average bubbleiresidence time in the rotating liquid of ea. 1/2 second. Communication of the liquid inlet ductgwith the core tank along a slight chord rather than precisely tangentially, as isy often required to facilitate fabrication, has proven satisfactory; in such case, if desired, a baffle may be provided at the inlet to divert the entering liquid stream as a sheet tangentially jetting along the inner wall of the core tank, with some increase in rotational velocity being thereby achieved. Vertical disposition of the polar axis is preferable, although disposition of the axis in any spatial di rection has proven satisfactory. With respect to the characteristics of liquid iiow in the vortex generated by the yFig'. 4 system, as delineated by. the Vsuperimposed dotted lines, it is found that the enter-ing liquid stream produces a turbulent region along the inner walls of the Spherical tank. This region, designated as region A,;, .f

has the fundamental vortex rotation, but there is a considerable component of velocity along the sphere walls by-passing the heart of the reactor. Nearthe central axis of the sphere and surrounding the vortex cavity, there are three vaguely defined, concentric cylindrical regions, B, C, and D, respectively, wherein the direction of 1 drift of the rotating liquid is up, down, and Aup, respectively. Between the outermost of the concentric cylinj drical regions, D, and the by-passing region A -along lo the tank walls, is a region E wherein the liquid driftis predominantly centripetal. In the Northern Hemisphere, the migration in region A directly to the liquid outlet pipe results in some liquid short-circuiting theheart of the core; in the Southern Hemisphere, shortcircuit 1 drift in region A fosters the upward driftin region D.` The upwarddrift in inner region B seems fostered by a downward drift in the next outer region C; lThe over-` all eifect of these drifts on the primary cemtripetal migra# tin is that the drifting liquid more rapidly shortcuts Vout of the core at the expense of some relative delay and' overheating of the liquid which enters region E. While this phenomenon may not be very serious at 1,000 kw. operation, it may ultimately prove particularly trouble some upon proceeding to operation yat considerably higher power densities. For such contingency, it has Ybeen found i that the phenomenon may be eliminated for the mostU part by-disposing afew streamlined baes, ns, or an inverted concentric bell-shaped palisade iixedin the bottorn of the tank to divert part of the updraft-in region D into region E; the best arrangement, though, comprises merely afxing a few slender horizontalrods ex-` tending from the tank walls to just short of the vvortex cavity. i In the case of the latter rods, the perpendicular j liquid flow in passing produces a turbulent pressure loss .35i behind them; the trailing low pressure area draws liquid n Y through the stagnant region E and into the region D updraft, with Wholesale mixing of the core contentsem suing, without signiicant obstruction of the liquid rotation. j' Y 40 The apparent optimum for such mixing rod arrange-mment is diagramrned in 4Fig.15. Here again a tangential inlet 500 -is disposed at ca. north latitude, aimed 30 south of the perpendicularl to the line ,of longitude of the point of introduction. A single slender radial rod 45 501, of length approximating of the `spheres radius extends inward from the core tank wall, inthe equatorial ;VV plane and at the th meridian from the inlet. A second slender radial rod 502, of the same length, isaixed at slightly to reduce their susceptibility to resonance vibraV tion and to increase strength at their base. Such arrangement gives evidence of constituting the minimum `amount .of rodding effective in bringing about effectivedestruction of the relative stagnation of region E in the dynarnicv vortex. Another method -showing particular promise for promoting thorough mixing in the vortex.

"comprises introducing a small supplemental stream of lfuel solution in its colder inlet condition directly into the center of thevortex throughthe south pole drain pipe;

being denser than the ambient hot solution at the center, -the colder liquid is centrifugally'thrown outward throught 'the vortex promoting considerable turbulence and mixing in its trajectory.

Finally, Figure 6 diagrams a simple arrangement, paralleling that of Figure 3, but incorporating a plurality of tangential liquid inlet means. Referring to Figure 6, the core tank 600 isragain precisely spherical, and, as in Figure 3, is provided at its north pole with a concentric nesting of afsurge'standpipe 601, a liquid discharge pipe :602,.anda gas discharge tube 603, and also, at its base,

va liquid drain pipe 604. The core tank 600 has a iirst v tangential equatorial liquid inlet duct 605, and, diametrically opposite thereto, a second tangential equatorial liquid inlet duct 606. In operation, tangential introduction of liquid through bothiof rthe liquid inlet ducts 605, 606, operates to maintain vortical rotation of enhanced vigor within the core tank 600.'

'Further illustration of the quantitative aspects and pre ferred conditions and procedures of the present method and means is provided in the following specific example.

Example A full-scale neutronic reactor, adapted to power an electric generating plant, substantially as illustrated in Figs. 1,72, 7 and 8 and having a core-tank system as diagrammed'in Fig. 4, has been constructed land successful-ly operated, as a prototype for like reactor systems of the same and much larger power production capacity, for both stationary industrial, andrnobile'propulsive applications. The general details of materials, dimensions,

and operational parameters, both for operation of the reactor at design point-i000 kw. iission reaction rate-and at 20% of design point power--200Vkwf-#are tabulated the 270th meridian, in the plane of the 30th parallel 50 Table IV below.

TABLE IV ILLUSTRATED IN FIGURES 1, 2, 4, 7 AN Percentage of Design Point Reactor OperatlonalPowerB-ate Reactor:

Power Level Net Power Output.

200 kw. to 1,000 kw.

Gross Power Output... 20 kw. 140 kw. Overall Eciency- 12% Volume of Cor#` Y 50 liters Power Density- 4 kW./l l 20 kw./l. Fuel Material. t UOgSOl in water, 30 g./1., U235 Percent Enhancement of Uranium in Um -Y 93.4 o Y. Um Consurnntinn 0.2 g./day l g./day. Y Y Um Required... v Y 2100 g. Core Tank:

Inside Diameter of 0ore 18 in. Thickness of Core Vessel-; A Y Ma in. Material of Core Vessel V347'Stainless Steel Pressure in Core Y Y -1000 p.s.i.a. Temperature in Core 250 O. (482 F.) (Outlet) Fabri ration All welded construction Core Connections: Y Y t f Inlet Duct 1% in. schedule 80* Outlet Pine Gas Outlet Pipe Surge Standpipn Drain Pipe M in. schedule 40 Reector Pressure Vesselz 3111..V Carbonsfpm..A

TABLE 1v-continued` Percentage oi Design Point Reactor Operational Power Rate Reector Pressure Vessel-Continued Pressure in Reflector Design Pressure Diameter of Bottom Flange and Cover... Thickness of Cover Volume of D20, full Reflector Inert Gas in Reilector ...4

Solution RecirculatingA System:

A. Recirculation# Flow Rate...- Type Pump Material of Pump Head at 100 gpm.- Efficiency Required Power..

Cooling Oil Requirements Residence Time in Core Tank Total External Holdup of Recirculation System. Holdup in Piping Holdup in Pum 1,020 p.s.i.a

100 gpm Canned Armature Centrifugal Pump.

Stainless Steel..

290 ft. Water (102 p.s.i. at 250 C.)

Percent Delay eutrons Lost Externally 16% Holdup in Uranium Solution Heat Exchanger Holdup in Pressurizer Residence Time in External System..

200 kw. Level 482 F Temperature of Solution, In Temperature of Solution, Out.- Operating Steam Pressure Operating Steam Temperature. Type of Heat Exchanger Shelltand U Tube Steam Genera or.

Materials Stainless Tubes, Steel She11 Tubing ln. O D., 18 gage Outside Heat Transfer Area of Tubes 75.5 sq. ft Number of Tubes 112 Length of Each Tube... 100 in. average length` Length of Heat Exchanger.. Diameter of Shell 26% in. I D-- H30 in Heat Exchanger 500 lbs... Pressure Drop of Solution Across Exchanger p.s.i.-. Velocity Through Tubes 15.8 ft./seo. v

C. Pressurizer- Operating Pressure Design Pressure p. Operating Temperature.. 285 C. (545 F.) Construction 347istainless 6 in. schedule 120 Volume of Vapor Space 0.364 cu. ft Heat Input Capacity 10 kw Steam Pressure to Pressurizer 1,500`p.s.i.-

D. Gas Separator and Reeombiner:

Rate iof25Cl0fsolvolution (HH-Or) (saturated) (1,000 80 cc./sec. Maximum Heat of Recombination 12 kw. Maximum Percent of Core Volume as Gas... 0. Bubble Residence Time in Core (secs.)

Reflector Rceirculating System:

A. Recirculation Flow Rate--. Type Pump Materials of Pump Head at gpm. Efficiency Required Power.. Cooling Oil Requirements.. Residence Time in Relector Residence Time, External Circuit.. External Hold-up..

Size of Piping i 26 gpm Canned Armature Centrifugal Pump.

Stainless steel ig ft. of water (36 p.s.i. at 100 0.)-

5.5 liters 1.5 liters sec.

1,000 kw. Level. 482 F.

400 ec./sec. Maximum.

58 kw. Maximum. 0.4. y

Velocity in Piping B. Deuterium Oxide Heat Exchanger 1,000 kw. Level.

Heat Load 132 kw. Temperature in Reflector 150 C. min. Temperature Boiler Feed Water, In-. E 131 F.

. ntering, 1,051 p.s.i ntering, 1,051 p.s.i. Pressure D20 Slde {Leavingy 1,020 p.s.i. Leaving, 1,020vp.s.i. Pressure, Water Side 500 p.s.i.a 220 p.s.i.a. Type of Heat Exchanger Double Pipe, Stainless Steel Area 505:1. ft Overall Heat Transfer Coclcient. 280 B.t.u./lu. ft.I F- Pressure Drop, D20 Power Cycle:

Flow Rate Boiler Feed Water... 6 gpm.

St 3,025.1b./hr.

200 p.s.i.a.

Turbine-generator Rating. 250 kw.

Boiler Feed W'ater Pump Power 5 H.P 5 H P.

Type Boiler Feed Water Pump Parallel Combination-elgetric powered piston pump, and

- ur me ump Turbine Condenser Load 500,000 B.t.u./hr 3,000,000 B.t.u./hr.

Turbine Condenser, Operating Pressure (design) 2 in Hg Turbine Condenser, Water In F Turbine Condenser, Water Out. F

Turbine Condenser, Water Flow. 10U-300 g.p.m 30D-600 g.p,m.

Turbine Condensate Temperature i 101 F.

Turbine Condenser. Water Main Size-. 5 in.

Turbine Condenser, Steam Main Size-. 4 ln., schedule 60 D' "11""TABLElV-Continuedi-l' y Y d y Percentageoi Design Point `Reactor Operational Power Rate d 1 20%` I y Y 100%l Dump System and Storage System:

A. Uranium Solution Storage System Total Volume of Storage Tanks 2681itcw I; Configuration of Storage Tanks.- 2 std, 8in. stainless pipes on 21 1 in.+centers, in parallel.'

Total Length of Pipe 25 ft. 6 i Types ot Uranium Solution Pressure-Letdown diaphragm-actuated' Ain. valve.

Throttling Valve.

1 ,r ,l Timeor EmergencyDumping Design Pressure of Storage Tanks Y Operating Pressure ,of Storage Tanks- 1 Eva orator: f

` eine Natural Convection, Double Y. Pipe.

` 1 rRate of Evaporation i 1301b. usin 60 .s.i. .steam Condensate Tanks: i g p g Construction 8 in. schedule 40 347 stainless x pipe. Total` Volume.. g 153 liters. Uranium Solution Diaphragm Pump Diaphragm with multiple check A Y l valves above and below: Head Y, l 1,000 p.s.l Flow Rate 1.15 gm m Suction Pressure 5 ft. H2O Loa 5 H.P 1 Economlzer Heat Exchanger: YD Coil Tube, and Shell Flow Rafe 1 g,n m i Rate ofHeat Removal 10,000 B.t.u./hr`

Condenser: j l Cooling Water FlOW 5 n* n m ea 27 sq. ft Overall Heat Transfer Coefi 85 B.t.1r./hr. ft2., F.- Maximum Heat Load. 150,000 B.t.u./hr Required Head, Water 10 fr Size Water Main 2 in, nip@ Temperature Cooling Water 80 G Tem erature Vapor Side: 194 F `IB..R =.i1ector u mp and Storage Systems- ATotal Vol e Configuration of Deuterium Oxide Storage Tanks;

, l centers.

Pressure Vessel Discharge Pipe. l 4 in Size D20 Pressure letdown Throttling Valve $4, in j Design Pressure of D10 Storage tanks.. v 970 p e i Operating Pressure or D20 Storage Tanks.-- 15 p.s.i. abs Time of Dumping 1,000 p.s.i 10-,30 sec 'Y Deuterium Oxide Diaphragm Pump Diaphragm pump with multipl 1 Y check valves above and below. 'Hand y FlOW RMA Y 2 n' p 'm Shield: ComDQiHf l Structural concrete, comprising Y Portland cement, barytes as aggregate, together with colemanite to provide 1% boron by weight and water. Thickness. V7 if Controls: l

Y Numberot Regulating Plates 1 i Aken/km of Regulating Plates 0.42%

Number ofSafety Plates Fixtures.-- n 2 Alun/k. cfleach Safety Plates Fixtures f 0.610/ Y Weight of each Plate 30 lbs Length of travel 18 in- Aken/km of reector between Full and Empty 6542-807 Time to flll Reflector (min) 1an Y Y Y ,Method of level control.. Automatic and also Manual 1 ,i remo e. Temperature Coefficient of It. at 250 C. .Free flow from -0.17%?C.

ore. 1 1 Minimum time for complete withdrawal of plates 120 secondsm-.

Neutron Flux (approximated): v Flux Neutrons/cm.v sec 200 kw. Level 1,000 kw. Level thermal epithermal" Y thermal epithermal Location Core 4X101 7X101 1. 9X101a 3. 7X101 v eector (inner edge) 2Xl01s 5X1()u 9)(1012 2. 3)(1013 Reflector (outer edge) l. 4x10l1 8X10m 7x10ll 4X1011 TotalNeui'rfms l. 5x10la neut./sec 7. 5x10 nent/sec Fission Products-1,000 kw. operation:

Equilibrium total quantity of fission products-.- ea. 2x10a curies- Rate of formation of gaseous fission productsca. 1.5 cc./hr., STP Equilibrium absorber content ca. 5 10i euries Xenon-135 stripping, 40 cc./sec. H1+0q@(200 kw) ca. 99+ percent Xenon-135 stripping, 0.4 crc/see. Hg-l-O ca. 95/

-Xenon-135 removal, equilibrium, 22.4 1 vapor space ca. 9607 II-235 Consumption= weight fission products ca. 1 g./day

F Schedule is employed, in customary manner, for conventional deflnition of the dimensions, weights, and sizes of steel pipeln accordance withrthe accepted A.S.A. Standard B-36.l0-1939, American Standards `Association, New York, N.Y. (cf. Chemical Engineers Handbook, edited by'I. H. Perry, third edition, pages 413-416 et seq., McGraw-Hill, 1950).

ASBy accepted and conventional definition, epithermal neutrons" are neutrons with energies abovethermal energy (ct. The

Elements of Nuclear Reactor Theory, Glasstone and Edlund, page 36, Sec. 3.13, Van Nostran 1952); y

Although this invention has been described with particular emphasis upon the rather highly developed speciiic reactor design, suitable for practical application, outlined .in the drawings, it is inherently susceptible to wide variation. For example, Kwhile utilization of' a single tangential inlet to sustain the vortex has been stressed, in higher-power operation use of Ia plurality of tanfgentially inlets, say four, symmetrically spaced around the equator, and associ-ated with a pair of' outlets, one at assumes primary significance. Furthermore, while operation with isotopically impure iissionableimaterial, such as U-235 accompanied by U-238 is oftenadvantageous in that U-238 becomes transmuted under the neutronv bombardment to Pu-239, thereby generating new ssionable material, nevertheless other advantages. such as achieving minimum reactor size and weight is afforded by operation with a completely isotopically isolated iissionable isotope-such as isotopically pure U-235'- whereupon no such transmutation to Pu-2`39 will obtain. On the other hand, the present system is lreadily adapted to extensive production of new iissionable material during operation, by merely enlarging the reactor core and incorporating a fertile material, such as natural thorium (Th-232) in the reector; thereupon, tbehigh neutron ilux transmutes the 'Ih-232 to 'Th-233, which iorthvvith spontaneously decays, through Pa-233, to iissionable U-233, which may be continuously recoveredduring Other variations and applications'ofthef` scription and example are illustrative only,`and donot`V limit the scope to the present invention.

What is claimed is:

taining lissionable material adapted to continuously'ow as a stream through a container means andio engage in self-sustaining chain fission reaction, with'concom'itant" substantial gas evolution, while maintained ina compact amassment within said container means, improved container means which comprises: an internally-unobstructedclosed container geometrically defining as'l its interior a volume of revolution about a principal axis through said interior; a liquid-inlet duct meansucommunicating:substantially tangentially with..the.interior. ofv saidcontainerin a direction generallyapproximating that of the-geo metric revolution. of. sm'd. volume; .meansdelining. agas-- outlet port substantiallvaxially concentric with, andat an axial extremity of, said container; and-meansvdeiir1ingv an annular liquid-outlet port substantiallyaxially concentric with, at the same axial `extremity with container zas, and surrounding, said means deining a gas-outlet port.

2. For improvedoperationof a neutronicreactorcomprising a liquid containing iissionable material adapted to be maintained in a compact amassment, andv while so amassed to engage in self-sustaining chain fission reaction with concomitant substantial gas evolution," a Amethod which comprises maintaining said liquid in said. compact.

periphery of said vortex and discharging said stream V`axially from said vortex, and discharging evolved gas as it concentrates within the cavity of the vortex. 3. The method of claim 2 wherein said liquid contain- -ing flssionable material is a solution of ssionable mate'- rial dissolved in a liquid solvent selected from the group" consisting of water and deuterium oxide. v

4. The. method of claim 2 whereinl said liquid containing tissionable material is an aqueous solution of iissionable material. l

5. Method ofv claim 2 wherein said ,amassment in rota- Y tional flow is maintained substantially spherical in conguration.

. 6. The method of claim 2 wherein said liquid' containing ssionable material is an aqueous solution' of uranyl sulfate, the uranium constituent of which is highly isotopically enriched in uranium-235.

7. The method of claim 2 wherein said liquid containing lissionable material is an aqueous solutionA of uranyl sulfate, the uranium constituent of which is highly isotopically enriched in uranium-235, maintained at approximately 250 C. temperature and approximately 1,000 p.s.i. pressure.

` able isotope in a liquid solvent selected from the group consisting of water and deuterium oxide, with the molar `ratio of said solvent to fissionable isotope in the solution maintained within the range of 250:1 to 100011.

1l. The method of claim2 wherein said liquid vin said amassment is maintained contiguous with a body of the same liquid in an expansion reservoirmeans external said amassment, said reservoir means being adapted to aioi'd direct and substantially uni'mpeded egressV from said vamassment of excess liquid content upon expansion of c amassment is maintained under substantial superatriios-v l. In a neutromc reactor comprising a..l1qu1d..conY

amassment in rotational flow about a principall axisof" the amassment at a'suiiicient-velocityto provide a vortex by continuously iiowing lsaidy liquid'asa-streamthrough said amassment, therein introducing said. stream of liquid forcefully into said.` amassment tangentially; at.y the adapted to be maintained in a compact'amassmentg'and? while so amassed to engage in self-sustaining chain fission reaction, with concomitant substantial radiationinduced decomposition of said liquid into gaseous components, a method which comprises maintaining said liquid in said compact amassment in rotational flow about Va principal axis of the amassment at a sufficient velocity to provide a vortex vby continuously owing said liquid as a stream through said amassment, therein'introducing said stream of liquid forcefully into said amassment tangentially at the periphery of said vo'rtexand l'dis" charging said'stream axially from said vortex,`the'reupon dischargingV decomposition gases asy they concentrate with the cavity ofthe vortex, and thereafter'eiecting chemical recombination ofthe resulting discharged gaseous-components, thereby reconstituting said liquid therefrom.

14. The method of claim 13 wherein 4said 'liqid'con' taining ssionable material is a solutioni of'ssionable material in a liquid solvent selected from thegro'up con? [sisting of water and deuteriumv oxide, wherein saidI radia- 

1. IN A NEUTRONIC REACTOR COMPRISING A LIQUID CONTAINING FISSIONABLE MATERIAL ADAPTED TO CONTINUOUSLY FLOW AS A STREAM THROUGH A CONTAINER MEANS AND TO ENGAGE IN SELF-SUSTAINING CHAIN FISSION REACTION, WITH CONCOMITANT SUBSTANTIAL GAS EVOLUTION, WHILE MAINTAINED IN A COMPACT AMASSMENT WITHIN SAID CONTAINER MEANS, IMPROVED CONTAINER MEANS WHICH COMPRISES: AN INTERNALLY-UNOBSTRUCTED CLOSED CONTAINER GEOMETRICALLY DEFINING AS ITS INTERIOR A VOLUME OF REVOLUTION ABOUT A PRINCIPAL AXIS THROUGH SAID INTERIOR, A LIQUID-INLET DUCT MEANS COMMUNICATING SUBSTANTIALLY TANGENTIALLY WITH THE INTERIOR OF SAID CONTAINER IN A DIRECTION GENERALLY APPROXIMATING THAT OF THE GEOMETRIC REVOLUTION OF SAID VOLUME, MEANS DEFINING A GASOUTLET PORT SUBSTANTIALLY AXIALLY CONCENTRIC WITH, AND AT AN AXIAL EXTREMITY OF, SAID CONTAINER, AND MEANS DEFINING AN ANNULAR LIQUID-OUTLET PORT SUBSTANTIALLY AXIALLY CONCENTRIC WITH, AT THE SAME AXIAL EXTREMITY WITH CONTAINER AS, THE SURROUNDING, SAID MEANS DEFINING A GAS-OUTLET PORT. 